Method and device for examining a biological tissue by analysing fluorescence response to illumination and for treating the tissue

ABSTRACT

Method, and the associated device, for examining a biological tissue, in particular dental tissue or tooth enamel of one or several teeth, the method including the steps of taking into account at least the fluorescence of the tissue detected in a first wavelength range and the fluorescence of the tissue detected in a second wavelength range. The device can be a surgery microscope with one or several filters. The filters can be swiveled into or out the Illumination beam path or the optical path of the light source of the device.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and device for examining abiological tissue by analyzing its fluorescence response to illuminationand for treating the tissue.

2. Discussion of Background Information

Practice discloses a plurality of methods for examining biologicaltissue. Some of these methods are based on the interpretation of afluorescence beam or radiation, which is emitted by the examined tissueupon the stimulation or excitation thereof. Thereby, by way of example,the intensity or the wavelength of the fluorescence beam or luminescenceare interpreted. Such a method is described in document U.S. Pat. No.4,479,499.

It is an object of the present invention to provide a further method forexamining biological tissue. In addition, it is aimed at presenting asuitable computing device, a corresponding monitoring system, a suitabletreatment apparatus as well as a digital storage medium, a computerprogramme product and a computer programme.

SUMMARY OF THE INVENTION

The object according to the present invention is solved by a method, acomputing device, a monitoring system, a treatment apparatus, and a setas set forth in the appended claims. The object according to the presentinvention is furthermore solved by a digital storage medium, a computerprogramme product and a computer programme, respectively, as also setforth in the appended claims.

The method for examining biological tissue according to the presentinvention may include taking into account at least one fluorescence ofthe tissue established or detected in a first wavelength range and afluorescence of the tissue established or detected in a secondwavelength range. Alternatively or in addition to taking into account asset forth supra the method may include measuring or assessing onefluorescence of the tissue established or detected in a first wavelengthrange and measuring or assessing a fluorescence of the tissueestablished or detected in a second wavelength range.

The computing device according to the present invention is suitable,programmed and/or configured for carrying out the method according tothe present invention in at least one embodiment thereof, in particularin conjunction with corresponding facilities or devices and/or acorresponding monitoring or diagnosis system.

The monitoring or diagnosis system according to the present invention(also referred to infra as monitoring system) comprises at least onedevice for taking into account at least the fluorescence of a biologicaltissue established in a first wavelength range, in particular of a toothor of a dental tissue, and of the fluorescence of the examinedbiological tissue established in a second wavelength range.

The treatment apparatus according to the present invention includes atleast one computing device according to the present invention and/or atleast one monitoring system according to the present invention or isconnected therewith.

Also, the present invention relates to a set comprising or consisting ofthe monitoring system according to the present invention and thetreatment apparatus according to the present invention.

A digital, particularly a non-volatile, storage medium according to thepresent invention, particularly in the form of a machine-readable datastorage device, particularly in the form of a floppy disk, CD, DVD orEPROM, in particular with electronically or optically readable controlsignals, can cooperate with a programmable computer system in such a wayas to trigger or prompt the mechanical steps of a method according tothe present invention or the control or regulation of a device of anapparatus according to the present invention.

Thereby, all, some or a few of the mechanical or automatic implementedsteps of the method according to the present invention can be triggered,prompted or executed.

A computer programme product according to the present invention includesa programme code stored on a machine-readable carrier for triggering,prompting or executing the mechanical steps of the method according tothe present invention or for controlling or regulating a device of asystem according to the present invention, when the computer programmeproduct runs or is executed on a computer. According to the presentinvention a computer programme product can be understood as, forexample, a computer programme which is stored on a storage device, anembedded system as a comprehensive system with a computer programme(e.g. an electronic device with a computer programme), a network ofcomputer-implemented computer programmes (e.g. a client-server system, acloud computing system, etc.), or a computer on which a computer productis loaded, executed, saved or developed.

A machine-readable carrier designates in certain embodiments of thepresent invention a carrier which contains software and/or hardwareinterpretable data or information. The carrier can be a floppy, a CD, aDVD, a USB stick, a flashcard, an SD card and the like.

A computer programme according to the present invention includes aprogramme code for triggering, executing or prompting the mechanicalsteps of the method according to the present invention or forcontrolling or regulating a device of a system according to the presentinvention, when the computer programme runs on a computer. A computerprogramme according to the present invention can be understood as, forexample, a physical software product, which is ready for distributionand contains a computer program.

It is also the case with the computer programme product according to thepresent invention and the computer programme according to the presentinvention that all, some or a few of the mechanically or automaticallyexecuted steps of the method according to the present invention aretriggered, prompted or executed by a device of an apparatus according tothe present invention.

The present invention also relates to using the monitoring systemaccording to the present invention together with the treatment apparatusaccording to the present invention.

Embodiments according to the present invention can include one orseveral of the features mentioned below. Embodiments according to thepresent invention are furthermore subject-matter of the dependentclaims.

In all following explanations, the use of the expressions “can be” or“can have” are synonymous with “is preferably” or “has preferably” etc.,and are to be understood as certain embodiments according to the presentinvention.

In certain embodiments according to the present invention, thebiological tissue (below also in short: tissue) is a tissue of apatient. The patient can be sick or healthy. The patient can be a humanbeing or an animal.

The examination of the tissue takes place in some embodiments in vivo,in others in vitro. In some embodiments according to the presentinvention, the biological tissue is a vital tissue, in others no vitaltissue. In certain embodiments according to the present invention, thebiological tissue is dental tissue or tooth enamel of one or severalteeth.

In some embodiments according to the present invention, taking intoaccount the fluorescence(s) determined in the first and/or the secondwavelength range corresponds to considering or observing them,incorporating them in further steps—in particular mathematical steps—ofthe method according to the present invention, optically displaying,processing (in particular mathematically processing) or interpreting (orrespectively (partial) steps thereof) the fluorescence(s) or at leastone signal or value allocated to this or these, comparing at least one,or more, of the fluorescences with each other, or comparing at leastone, or more, of the fluorescences or at least a signal or valueallocated to said fluorescence(s) with at least one threshold value orwith at least one reference range (e.g., for each fluorescenceseparately, or for a ratio thereof, or for the signal), and/or recordingand/or storing by means of optical systems, in particular camerasystems, basing a result or an assessment of said examined tissue, orany combinations thereof. In certain embodiments according to thepresent invention, taking into account includes at least one of theaforementioned ways of consideration.

In certain embodiments according to the present invention, fluorescenceis understood as a tissue property, for example the amplitude, theintensity or the size of a radiation of the tissue obtained or observedin response to excitation by any or a pre-determined light (for examplepre-determined regarding its wavelength(s)), in particular under or withparticular wavelengths.

In some embodiments according to the present invention, fluorescencemeans a direct or indirect size or amplitude of a fluorescenceradiation, but not the radiation itself.

In particular embodiments according to the present invention theestablished fluorescence means an observed or a measured fluorescence ora fluorescence established from known or measured or calculated orotherwise determined values or derived from tables or the like.

In certain embodiments according to the present invention a wavelengthrange is a range including a radiation (in particular an opticalradiation) under one or several wavelengths. A wavelength can hence bedefined by stating the length of their waves in nanometers (nm).

In certain embodiments according to the present invention, the methodaccording to the present invention does not include making a diagnosis.

In some embodiments according to the present invention, the method doesnot include comparing the knowledge or information acquired by means ofthe present invention with patient data already present, in particularthose of a collective.

In certain embodiments according to the present invention, the methodexclusively relates to the recognition or the assessment of a physicalproperty of the studied biological tissue.

In certain embodiments according to the present invention, thefluorescence of radiation is taken into account from exactly twowavelength ranges. Everything said herein in combination with two ormore wavelength ranges relates in some embodiments according to thepresent invention to exactly two wavelength ranges.

In certain embodiments according to the present invention, thefluorescences of several wavelength ranges are taken into accountsimultaneously. In certain embodiments according to the presentinvention, simultaneously taking into account means or includes takinginto account at the same time. In some embodiments according to thepresent invention, taking simultaneously into account means or includescreating and/or using a common signal resulting from the fluorescence ofseveral wavelength ranges. Such a signal can have the form of a quotientor ratio or a pair of values.

In certain embodiments according to the present invention, taking intoaccount consists of creating a common signal, which indicates afluorescence qualitatively or quantitatively, or comprises such a step.Such a signal, or part-signal, may in some embodiments according to thepresent invention be gathered from or generated for each of thewavelength ranges independently from any other wavelength range. Such asignal may in certain embodiments according to the present invention beobtained by picking the highest intensity of all wavelengths of thewavelength range in question. Such a signal may in some embodimentsaccording to the present invention be obtained by calculating anarithmetical average or an arithmetical median of the intensities of allconsidered wavelengths of the same wavelength range.

In particular embodiments according to the present invention, the firstand/or second wavelength range comprises one wavelength.

In certain embodiments according to the present invention, the relativeor the absolute intensities of the fluorescences in the at least twowavelength ranges are added to form a common signal or otherwisesupplemented.

In some embodiments according to the present invention, thefluorescences of several wavelength ranges are taken into considerationto represent or display them simultaneously in an image, a film, etc.

In certain embodiments according to the present invention, taking intoaccount the fluorescences of several wavelength ranges means or includestaking into consideration relative intensities of the fluorescences,optionally within the at least two wavelength ranges or between them,optionally related to reference values.

In some embodiments according to the present invention, the firstwavelength range is or extends over a range from 500 nm to 520 nm orcovers said range.

In certain embodiments according to the present invention, the secondwavelength range is or extends over a range from 614 nm to 685 nm orcovers said range.

In some embodiments according to the present invention, the firstwavelength range is defined or determined as narrower than the secondwavelength range. If the second wavelength range is for instance 20 nm(nanometer) wide, in which it includes wavelengths about between 620 nmand 640 nm, so the width of the first wavelength range is smaller than20 nm.

In certain embodiments according to the present invention, the first andthe second wavelength range do not overlap each other.

In some embodiments according to the present invention, none of thewavelength ranges taken into account overlaps any of the otherwavelength ranges also taken into account.

In certain embodiments according to the present invention, thecombination of the first wavelength range and of the second wavelengthrange includes a first pass band of 500 nm to 520 nm and a second passband of 614 nm to 685 nm.

In other embodiments according to the present invention, the wavelengthsof the first pass band range from 500 nm to 555 nm and those of thesecond pass band range from 614 nm to 675 nm.

Additional combinations according to the present invention of the firstpass band range and second pass band range are as follows:

480-500 nm and 600-660 nm

485-505 nm and 620-690 nm

500-510 nm and 620-650 nm

550-560 nm and 610-650 nm

In some embodiments according to the present invention, the lowercut-off or threshold wavelength of the first wavelength range equals orexceeds 460 nm.

In certain embodiments according to the present invention, the uppercut-off or threshold wavelength of the second wavelength range is notlimited.

In some embodiments according to the present invention, the wavelengthranges located between the considered wavelength ranges are taken intoaccount.

In certain embodiments according to the present invention, the upperlimit of the first, lower wavelength range and the lower limit of thesecond, higher wavelength range are 5 nm or more apart from each other.In other embodiments according to the present invention, these twolimits are 10 nm or more apart from each other. In further embodimentsaccording to the present invention, these two limits are 60 nm or moreapart from each other.

In certain embodiments according to the present invention, the methodincludes measuring the fluorescence radiation issued by the biologicaltissue, in at least two wavelengths or wavelength ranges.

In certain embodiments according to the present invention, the methodincludes measuring the fluorescence beam or radiation by using at leastone double bandpass filter.

A double bandpass filter means in some embodiments according to thepresent invention a filter, which lets through radiation, in particularfluorescence radiation, from two predetermined wavelength ranges, butdoes not let through radiation of a wavelength which cannot be allocatedto any one of two predetermined wavelength ranges.

Analogically to the double bandpass filter, in certain embodimentsaccording to the present invention, a triple, quadruple, etc. bandpassfilter can be implemented when more than two wavelength ranges areconsidered.

In some embodiments according to the present invention, when using thedouble bandpass filter as well as when using a triple, quadruple etc.bandpass filter, the filtering component and/or the filtering functionis a complete, i.e. single, filter, or is realised by means of acomplete filter. In other embodiments according to the presentinvention, the function of the double or multiple bandpass filter isdivided into two or more components which are separate from each other.Components that are separate from each other can be incorporatedparallel or alternately, possibly with a rapid changeover in therespective optical path (for example, the way along which light travelsfrom an object or tissue under examination to a sensor, filter or lens,or the way along which light travels from a sensor, filter or lens tothe eye of the observer, or vice versa).

In certain embodiments according to the present invention, the bandpassfilter, in particular the double bandpass filter, is a combination of atleast one pass filter, for instance, one long pass filter, and at leastone notch filter, or includes such a combination.

A notch filter, also known as a Kerb-filter, can be provided as anelectronic filter. Frequencies or wavelengths within a predetermined,for example a narrow wavelength or frequency range, can be filtered outby means of a notch filter. Notch filters can be provided as bandelimination filters, also called frequency elimination or blockingfilters or frequency traps.

In certain embodiments according to the present invention, the double ormultiple bandpass filter is used for RGB (red-green-blue) colour channelseparation. This way, a more efficient RGB channel separation of thecolour camera utilised can be achieved. This method makes it possible toobtain, in particular with a QLF method (Quantitative Light-inducedFluorescence), advantageously better signal qualities.

In certain embodiments according to the present invention, theobservation filter in use (for example provided as a double bandpassfilter) and/or the illumination filter in use are non-digital filters.Similarly, in certain embodiments the present invention is based onnon-digitally filtering, taking into account non-digitally analysis,non-digital processing and/or non-digital assessment, and so on, orincludes them.

The observation filter utilised, in particular the bandpass filter, canbe an optical filter. In certain embodiments according to the presentinvention, the observation filter is a dichroic filter.

In certain embodiments according to the present invention, themonitoring system can be arranged or configured to perform or to allow aso-called “boost”-function. A boost function is in certain embodimentsaccording to the present invention an upward regulation which takesplace particularly as a short-time, in particular time-limited upwardregulation, an increase or amplification of the illumination of theemitted light, or (respectively) of the intensity thereof, in particularover a predetermined time period.

Some embodiments according to the present invention provide for theactivation of such a boost function when pivoting the filter, forinstance the illumination filter or the observation filter, into aradiation or observation path, or the activation of a corresponding orpredetermined filter position. Alternatively, such a boost functionstarts when a further or another component of the monitoring system isbeing activated, for example a mechanically movable component, a switchor the like.

In certain embodiments according to the present invention, the boostfunction, as described supra, is activated automatically and/ortriggered by a pivoting motion, as illustrated above, of at least one ofthe filters or when operating a further or another component of themonitoring system.

In some embodiments according to the present invention, the methodincludes illuminating the biological tissue by illumination waves inorder to obtain a fluorescence radiation. Other embodiments according tothe present invention do not include such an illumination.

In some embodiments according to the present invention, the methodincludes illuminating the biological tissue by illumination waves whichhave a wavelength or wavelengths that are smaller than the wavelength(s)of the first wavelength range.

In certain embodiments according to the present invention, the methodincludes illuminating with waves of a wavelength range comprisingwavelengths between 350 nm and 500 nm, in particular between 370 nm and440 nm, in particular between 39.8 nm and 437 nm, or being limitedthereto.

In certain embodiments according to the present invention, theillumination includes waves of a wavelength range which is arrangedsymmetrically with regard to 405 nm. By way of example, the wavelengthrange of the illumination waves includes wavelengths from 370 nm to 440nm.

In some embodiments according to the present invention, the methodincludes illuminating the biological tissue (exclusively or incomplement thereto) by means of one or of several light-emitting diodes(LED) and/or by means of a laser.

In certain embodiments according to the present invention, the computingdevice is connected to control or regulation units, in particular of atreatment apparatus, in signal communication, or includes such elements.

The apparatuses according to the present invention include in certainembodiments according to the present invention devices or means forperforming some or all of the method steps mentioned herein.

In certain embodiments according to the present invention, the devicesmentioned in this context or required for their performance are means,devices, etc. which are not only suitable for the respective stated use,but also explicitly provided, configured, programmed, etc. to that end.

In some embodiments according to the present invention, the monitoringsystem includes at least one of a device for measuring, an (observationor illumination) filter or a filter arrangement, which (completely or inat least one section thereof) is arranged such that it can be moved ortransferred, preferably by hand or by actuating or pushing a foot pedal,for example, by the observer who might be the dentist and, for example,via a lever, handle, a feeder, a pusher or any other filter movingdevice, from a first position, in which it is not arranged in an opticalpath (or in the respective optical path in question), into a secondposition, in which it is arranged in the optical path. It may bearranged to be pushed, pivoted, rotated, inserted, etc., or for atransfer.

In certain embodiments according to the present invention, themonitoring system is a camera for continuing image acquisition, forinstance for creating a film, or includes such an element. In otherembodiments according to the present invention, it does not.

In some embodiments according to the present invention, the monitoringsystem includes a device for superimposing white light (for example, thelight having the color of light that contains all of the wavelengths ofthe visible spectrum without absorption) onto an optical representationor illustration of said at least one fluorescence of the tissueestablished in a first wavelength range and of a fluorescence of thetissue established in a second wavelength range.

In particular embodiments according to the present invention, themonitoring system or the treatment apparatus includes a handle or ahand-held device, in or on which a device for illuminating thebiological tissue by illumination waves for obtaining a fluorescenceradiation is provided.

In certain embodiments according to the present invention, themonitoring system or the treatment apparatus comprises a device forilluminating the biological tissue by means of illumination waves forobtaining or triggering a fluorescence radiation. This device forilluminating is in some embodiments according to the present inventiondesigned or arranged to be movable with respect to further sections ofthe treatment apparatus or the monitoring system, or both, while usingthe monitoring system or the treatment apparatus. The further sectionsmay include one or more of the illumination filter, the observationfilter, the lever for moving a filter into an optical path, and thelike.

The device for illuminating is designed in some embodiments according tothe present invention as illumination fibres, light guide, opticalconductor, or fibre optics.

In some embodiments according to the present invention, the monitoringsystem is a microscope, an operational microscope, a surgery microscope,a dental microscope, a head-carried or head-set microscope, magnifyingglasses, a digital microscope or the like, or comprises such a device orsuch devices. In certain embodiments according to the present inventionthe aforementioned devices are optical devices and/or light devices,such as light microscopes, light magnifying glasses and the like. Insome embodiments according to the present invention the aforementioneddevices do not comprise a wavelength division multiplexer (WDM) and/or acharged-coupled device (CCD), or consist thereof. In particularembodiments according to the present invention the aforementioneddevices are not a digital camera or not interconnected with a digitalcamera or both.

In certain embodiments according to the present invention the treatmentapparatus is a device for treating the biological tissue. It can, inparticular, be a dental drill or a device for removing dental calculus,stains or tartar, or comprise such a device or such devices.

The treatment apparatus comprises in some embodiments according to thepresent invention a device for automatic interruption of the treatment.The device may interrupt the treatment depending on or on the basis ofthe at least one fluorescence of the tissue established in the firstwavelength range and/or the fluorescence of the tissue established inthe second wavelength range. This takes place, for instance, after theemitted fluorescence(s) and/or the signal derived therefrom has beencompared with a reference or threshold value or with a reference orthreshold range, or the like.

All advantages achievable by the method according to the presentinvention can also be attained in certain embodiments according to thepresent invention with each of the devices and apparatuses according tothe present invention. This is also true of some embodiments accordingto the present invention for the digital storage medium according to thepresent invention, the computer programme product according to thepresent invention and also the computer programme according to thepresent invention.

Methods for exciting tissue by light in order to make it emit afluorescence beam and methods for analysing the measured fluorescenceare known to the skilled person from, for example, the U.S. Pat. No.5,503,559 to Sandor G. Vari, and from the German patent application filefor Ferton Holding S. A., laid open under DE 10 2007 047 093 A1, each ofwhich is expressly incorporated herein in its entirety by referencethereto.

In certain embodiments according to the present invention, the setcomprises or consists of the monitoring system according to the presentinvention and the treatment apparatus according to the presentinvention, wherein the monitoring system comprises the observationfilter and wherein the treatment apparatus comprises the device (orsource) for illuminating the biological tissue. In some of thoseembodiments, the device (or source) for illuminating the biologicaltissue is comprised in a hand-held tool, for example a dental drill.

Some, a few or certain embodiments according to the present inventionpresent one, some or all of the following and/or the aforementionedadvantages:

An advantage of some embodiments according to the present invention isthat a signal can be generated which is strong enough and/orinterpretable enough when taking account or considering the fluorescenceradiation of several wavelength ranges, so as to represent tissueproperties such as tooth decay or caries, even, partially, in continuousdisplay such as on a film. In this aspect, the procedure according tothe present invention may advantageously differ from the state of theart. This holds true, first of all, if, as usual in the prior art, onlyfluorescence radiation of one wavelength range is taken into account. Incertain embodiments according to the present invention, it can hence bepossible for the user or the dentist to advantageously detect toothdecay or caries as red areas in an otherwise green fluorescentenvironment in the healthy tooth, optically with prominence and, hence,in an easy way.

Furthermore, to detect a certain tissue property such as tooth decay orcaries, the user does not need any camera and/or, in particular, morecostly illumination of the tissue or tooth. The observation can takeplace by means of the human eye alone without using digital cameratechnique. Consequently, the tissue or the tooth can be assessed bymeans of a surgery microscope or treatment apparatus.

Moreover, it is advantageous to be able in certain embodiments accordingto the present invention to consider and/or to interpret thefluorescences in question in the course of a treatment of the tissue,for example the tooth treatment. In this aspect, the present inventiondiffers advantageously in the corresponding embodiments from thedisclosure of, by way of example, the document U.S. Pat. No. 4,447,499which is mentioned in the introduction of this specification.

A further advantage of some embodiments according to the presentinvention is that a treatment of the tissue, for example a tooth, neednot be interrupted for controlling the tissue properties of the tooth.Rather, the treatment may unfurl under permanent “live” control of thestatus of the tooth by the treating dentist. With certain embodimentsaccording to the present invention, it is not necessary to changeinstruments between the treatment apparatus and the monitoring systemand vice versa.

Due to or by means of the selection of the width of the pass band rangesand/or of the spacing of the fluorescence radiation taken into accountfrom different wavelength ranges or filter pass band ranges, thesensitivity and the discrimination capacity of the eye can be usedadvantageously. The sensitivity as well as the discrimination capacityare established optimally with the aforementioned wavelength ranges, inparticular due to their width and position in the radiation spectrum onthe one hand as well as relative to one another on the other hand.

If, like in some embodiments according to the present invention, thewidth of a red fluorescing wavelength range is found to be larger thanthe width of a green fluorescing wavelength range, then the fact thatcertain colours are perceived more strongly by the human eye than othersis advantageously taken into account. Setting of correspondingdistinctly wide wavelength ranges for fluorescence radiation canadvantageously ensure a desired balance of the signal portions. It canalso ensure that certain information about the examined tissue does notget lost and is preferably registered as reliably as it should.

Providing a device for illuminating within the meaning of the presentinvention, i.e. for exciting the tissue in question, in the handle of adrill or any other dental or endodontic tool, as is contemplated forcertain embodiments according to the present invention, mayadvantageously increase a common manageability or use of the drill ortool and the monitoring system.

The use of radiation of corresponding LED and/or laser beams mayadvantageously dispense with having to resort to illumination filters.This may enable an advantageously straightforward design of the systemaccording to the present invention, which is also achievable accordingto the present invention.

The use of radiation of corresponding LED and/or laser beams can,moreover, advantageously enable amplification of the illuminationgenerated by the monitoring system. Shortcomings which may result forinstance from illumination by means of halogen spotlights, which displaya so-called “blue weakness”, can thus be advantageously avoided.

The automatic interruption of a treatment, for instance of a tooth, bymeans of the treatment apparatus according to the present invention ofcertain embodiments can advantageously ensure that any undesirabletreatment of a healthy or non-carious dental tissue is advantageouslyavoided.

The superimposition of results, which can be achieved by certainembodiments of the present invention, with illustrations known to theuser of the system, for example white-light images, allows forsuperimposition of several pieces of information, which are respectivelyrelevant per se, with the advantage of easier orientation.

Transferability of a or any filter or filter arrangement mentionedherein from a first position, in which it is not lying in an opticalpath and/or not acting as a filter, into a second position, in which itdoes filter, may advantageously enable the use of one and the samesystem without the need to change instruments in different applicationsto enable various pieces of information to be obtained.

More advantages may arise from the combination of the multiple or doublebandpass filter with the surgery microscope here suggested for someembodiments according to the present invention. A surgery microscope isthus characterised by relatively large working distances, wherein aworking distance means the distance between an object or tissue and thesurface of the first lens lying in the optical path (seen from theobject). Due to the relatively large working distances, daylight orambient light always falls onto the object as well. Through the use andeffect of a double or multiple bandpass filter in or on the surgerymicroscope, as suggested according to the present invention,fluorescence images can be created or achieved which are not—or only toa minimal extent—disturbed by daylight or ambient light fallinglaterally (because of the working distance).

Another advantage which ought to be stressed is that the tissue may beobserved with the naked eye. Moreover, there is no need to take apicture of the tissue using a camera for assessing same later on.Rather, it is possible and provided for in certain embodiments accordingto the present invention that the tissue can be directly observed, i.e.without using a camera system.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described below with reference to theappended drawing purely by way of example. In the drawing, identicalreference numerals designate similar or identical elements. In thedrawing,

FIG. 1 shows an example of a monitoring system according to the presentinvention in overview;

FIG. 2a shows the monitoring system according to the present inventionof FIG. 1 with a filter snifter in a first position;

FIG. 2b shows the monitoring system according to the present inventionof FIG. 1 with a filter snifter in a second position;

FIG. 3 shows the filter snifter of FIGS. 2a and 2b in isolatedperspective representation;

FIG. 4 shows as a block diagram schematically the assembly of themonitoring system according to the present invention of FIGS. 1, 2 a and2 b;

FIG. 5 shows schematically simplified a possible cooperation of thedevices according to the present invention; and

FIG. 6 shows schematically simplified the basic idea of a double bandfilter having a combination of a long pass filter and a notch filter.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an example of a monitoring system according to the presentinvention 100 in overview. The monitoring system 100 is based on anextended surgery microscope OPMI Pico with S100 stative from the CarlZeiss company, Germany. The monitoring system 100 has a foot 101, astand 103 (maybe adjustable in height) and a superstructure 105 fittedwith a microscope unit 107.

The foot 101 can include, as in the example of FIG. 1, two, three, fouror more rollers 109 for ensuring the mobility of the monitoring system100.

The microscopy unit 107 exhibits at least one ocular or two oculars 111,as shown by way of example in FIG. 1.

The microscopy unit 107 is adjustable by means of one or several jointsin their three-dimensional orientation for the examiner.

The microscopy unit 107 includes for easy positionability in space atleast one handle or—as shown by way of example in FIG. 1—two handles113.

FIG. 2a shows the microscopy unit 107 of the monitoring system 100according to the present invention in FIG. 1. The microscopy unit 107comprises a filter snifter 200 which cannot be seen for illustrationpurposes in FIG. 1.

The filter snifter 200 can be pivoted by means of a pivot lever 201between different positions, but at least between a first and a secondposition.

FIG. 2a shows the filter snifter 200 in the first position. In saidfirst position, the filter(s) provided in or on the filter snifter 200are swiveled into an optical path of the corresponding beam or light sothat filtering takes place. Said swiveled-in mode corresponds to thefirst position of the filter snifter 200 illustrated in FIG. 2 a.

The corresponding filter(s) can be observation filters, which areswiveled into the optical path of observation or into the detected beamor the detected light, i.e. into the optical path between the object ortissue being studied and the ocular.

Similarly, one or several illumination filters can be swiveled into orout of the corresponding illumination beam path by means of the filtersnifter, which is illustrated in the figures, or by means of a filtersnifter, non illustrated in the figures, in complement to, oralternately to, swiveling the observation filter(s), hence, into theoptical path from the light source to the considered object or tissue.

Instead of the filter snifter 200 the device the monitoring system orthe treatment apparatus according to the present invention may have anydevice that is configured to move one or more filters into the opticalpath or out of it. Swiveling is just one example. Any other movement isalso encompassed by the present invention.

FIG. 2b shows, within the illustration of FIG. 2a , the microscopy unit107 of the monitoring system 100 according to the present invention inFIG. 1, whereby the filter snifter 200 is in a second position, whichcan be seen, in comparison to FIG. 2a , from the position of the pivotlever 201. The pivot lever 201 can carry observation filters and/orillumination filters and swivel them along when it moves.

In the second position shown in FIG. 2b , the corresponding filters areswiveled out of the optical path so that no filtering takes place.

FIG. 3 shows the filter snifter 200 of FIGS. 2a and 2b , schematicallysimplified, in isolated perspective representation.

FIG. 4 shows as a block diagram schematically an assembly 300 of themicroscope unit 107 of the monitoring system according to the presentinvention of the previous figures. The block diagram shows theillumination optical path from the light source to the object or tissue,and the observation optical path from the object or tissue to the ocularof the microscopy unit 107.

The assembly 300 comprises a light source 301. Said source can bedesigned as a halogen radiator or spotlight or Xenon radiator orspotlight. It may, in addition, contain one or several LED or laserbeams.

The illumination beam coming out of the light source 301 enters anoptionally provided heat protection filter 303. A fibre optic or lightconductor 305 is provided subsequent to the heat protection filter 303.The light exiting the heat protection filter is optionally filtered inan illumination filter 307. The illumination filter 307 is designed insome exemplary embodiments of the present invention as a short passfilter. The illumination filter 307 can be designed to let through lightof the wavelength below 440 nm. The light passing through theillumination filter 307 hits a studied object, here a tooth 309. Thefluorescence radiation emitted by the tooth 309 runs through anobservation filter 311 and can be examined subsequently by the oculars111. The observation filter can be a double bandpass filter. The lightemitted by the tooth 309 or the fluorescence emitted therefrom can alsobe filtered with any other filter which the person skilled in the artmay deem appropriate.

In this exemplary embodiment according to the present invention, theillumination filter 307 as well as the observation filter 311 can,respectively, independently of each other, be swiveled into thecorresponding optical path or swiveled out of said path.

FIG. 5 shows, simplified, a possible cooperation of the devicesaccording to the present invention, which are illustrated schematicallyand grossly simplified.

The monitoring system 100 includes a computing device 400 In the exampleof FIG. 5. The monitoring system 100 is in signal communication, asindicated by the arrows, with a treatment apparatus 500. The signalcommunication can be a single-direction control unit, or a reciprocallyoperating regulating unit.

It is noted that a computing device 400 according to the presentinvention can be in signal communication with regulating or controldevices of the treatment apparatus 500 according to the presentinvention. This is not the case in other embodiments according to thepresent invention. In some embodiments according to the presentinvention, no computing device 400 according to the present invention isprovided.

FIG. 6 shows in a simplified diagram the basic idea of a double bandfilter, which is a combination of only one long pass filter and onenotch filter.

Thereby, the reference sign 601 designates the transmission function ofthe notch filter, 602 designates the transmission function of the longpass filter and 603 designates the total transmission function of thedouble band filter described with reference to FIG. 6.

REFERENCE NUMERALS

-   100 Monitoring system-   101 Foot-   103 Stand-   105 Superstructure-   107 Microscopy unit-   109 Rollers-   111 Oculars-   113 Handles-   200 Filter snifter-   201 Pivot lever-   300 Assembly-   301 Light source-   303 Heat protection filter-   305 Fibre optics-   307 Illumination filter-   309 Tooth-   311 Observation filter-   400 Computing device-   500 Treatment apparatus-   601 Transmission function of the notch filter-   602 Transmission function of the long pass filter-   603 Total transmission function

What is claimed is:
 1. A method for examining biological tissue, whereinthe method comprises: illuminating the biological tissue to be examinedby illumination radiation emitted by a light source along anillumination optical path to cause the biological tissue to emitfluorescence radiation; filtering the emitted fluorescence radiation bya filter positioned in an observation optical path to generate an imageof the biological tissue based on the filtered fluorescence radiation,which image is capable of at least one of (i) being observed and (ii)being recorded and optically displayed; the filter being a doublebandpass filter comprising a combination of a longpass filter and anotch filter and having a first passband within a wavelength range offrom 460 nm to 560 nm and a second passband within a wavelength range offrom 600 nm to 685 nm, the first passband and the second passband beingapart from one another by at least 60 nm.
 2. The method of claim 1,wherein the illumination radiation has a wavelength within a wavelengthrange of from 370 nm to 440 nm.
 3. The method of claim 1, wherein themethod further comprises moving the filter in and out of the observationoptical path.
 4. The method of claim 1, wherein the observation opticalpath is that of a surgical microscope.
 5. The method of claim 1, whereinthe first passband is narrower than the second passband.
 6. The methodof claim 1, wherein the first passband extends from 500 nm to 520 nm,overlaps therewith or lies within that range.
 7. The method of claim 1,wherein the second passband extends from 614 nm to 685 nm, overlapstherewith or lies within that range.
 8. The method of claim 6, whereinthe second passband extends from 614 nm to 685 nm, overlaps therewith orlies within that range.
 9. The method of claim 1, wherein the notch ofthe notch filter is superimposed in a wavelength range within which thelongpass filter has a high transmission.
 10. The method of claim 1,wherein the method further comprises interrupting an operation of atreatment device based on an evaluation of an intensity of the filteredfluorescence radiation.
 11. The method of claim 1, wherein the method isused for determining the presence or absence of tooth decay or carries.12. The method of claim 1, wherein the generated image is capable ofbeing observed.
 13. The method of claim 1, wherein the generated imageis capable of being recorded and displayed.
 14. An apparatus forexamining biological tissue, wherein the apparatus comprises: a lightsource which provides illumination radiation for illuminating an object;an illumination optical path from the light source to the object; atleast one of an ocular for viewing an image of the illuminated objectand a camera for recording an image of the illuminated object; anobservation optical path from the object to the at least one of anocular and a camera; a filter positioned in the observation opticalpath, which filter is a double bandpass filter comprising a combinationof a longpass filter and a notch filter and having a first passbandwithin a wavelength range of from 460 nm to 560 nm and a second passbandwithin a wavelength range of from 600 nm to 685 nm, the first passbandand the second passband being apart from one another by at least 60 nm.15. The apparatus of claim 14, wherein the apparatus further comprises afilter snifter capable of assuming a first snifter position in which thefilter is positioned in the observation optical path and a secondsnifter position in which the filter is positioned outside theobservation optical path.
 16. The apparatus of claim 14, wherein thelight source emits illumination radiation within a wavelength range offrom 370 nm to 440 nm.
 17. The apparatus of claim 14, wherein the lightsource emits illumination radiation within a wavelength range of from398 nm to 440 nm.
 18. The apparatus of claim 15, wherein the lightsource emits illumination radiation within a wavelength range of from370 nm to 440 nm.
 19. The apparatus of claim 18, wherein the lightsource emits illumination radiation within a wavelength range of from398 nm to 440 nm.
 20. The apparatus of claim 14, wherein the firstpassband is narrower than the second passband.
 21. The apparatus ofclaim 14, wherein the first passband extends from 500 nm to 520 nm,overlaps therewith or lies within that range.
 22. The apparatus of claim14, wherein the second passband extends from 614 nm to 685 nm, overlapstherewith or lies within that range.
 23. The apparatus of claim 14,wherein the notch of the notch filter is superimposed in a wavelengthrange within which the longpass filter has a high transmission.
 24. Theapparatus of claim 14, wherein the apparatus comprises an ocular forviewing an image of the object.
 25. The apparatus of claim 14, whereinthe apparatus comprises a camera for recording an image of the object.26. The apparatus of claim 18, wherein the apparatus is a surgicalmicroscope comprising a microscope unit with at least one ocular unitand an adjustable stand.
 27. The apparatus of claim 18, wherein theapparatus is a digital microscope comprising a camera for recording agenerated image based on filtered fluorescent radiation emitted by theobject in response to being illuminated by light from the light sourceand a display unit for displaying the recorded image.
 28. A treatmentsystem, wherein the system comprises a treatment device, a control forthe treatment device, and the apparatus of claim 14, the apparatus beingin signal communication with the control for the treatment device. 29.The system of claim 28, wherein the light source of the apparatus emitsillumination radiation within a wavelength range of from 370 nm to 440nm.